Eclipse Mosquitto

Eclipse Mosquitto is an open-source MQTT broker with companion client tools for Linux, macOS, Windows and self-hosted deployments. It suits developers and operators building IoT messaging around sensors, embedded systems or servers who want direct control of the broker. The trade-off is that operating it and obtaining support largely remain your responsibility.

Overview

Mosquitto implements MQTT 5.0, 3.1.1 and 3.1, using MQTT’s publish/subscribe model to move messages between devices without requiring each device to communicate directly with every other device. That model fits low-power sensors, phones, embedded computers and microcontrollers, and the project names manufacturing, healthcare, automotive and smart-home systems as application areas.

Its lightweight design is a practical advantage when the broker must run on a low-power single-board computer, while remaining suitable for full servers. Deployment is self-hosted and on-premises, so you retain control of the environment but must provide and maintain that environment yourself.

Key features

Broker and client tooling

The core broker supports MQTT and MQTT over WebSockets. Delivery guarantees are configurable, allowing deployments to choose behavior appropriate to their messaging requirements rather than accepting one fixed policy. The project also supplies a C library for building MQTT clients, plus the mosquitto_pub and mosquitto_sub command-line clients. Those tools are useful for development, scripting and straightforward operational checks alongside the broker.

Security and testing

Mosquitto directs vulnerability reports through the Eclipse Security process and publishes past security issues and fixes. A public test MQTT server offers plain MQTT, TLS, client-certificate TLS and WebSocket options, giving teams a place to exercise connection methods before putting their own broker into service.

Related tooling and support

Streamsheets uses Mosquitto as a core component and can process incoming MQTT data. Community help is offered on a best-effort basis through GitHub, a mailing list, Matrix and Cedalo forums. Cedalo also provides hosted or on-premises instances, consulting and custom development when a project needs commercial assistance beyond community channels.

Pricing

The Open-source Mosquitto plan costs nothing. It includes core MQTT features and on-premises deployment, with no paid tier, seat count or usage quota stated. This is a strong fit for teams comfortable running their own infrastructure and selecting their own operational safeguards; it is less suitable if you want a managed service included in the software plan.

There is no trial or renewal term to manage because the plan is free. Commercial hosting, consulting and custom development from Cedalo are separate service options, with custom pricing.

Platforms

Mosquitto runs on Linux, macOS and Windows, as well as self-hosted environments. Windows downloads include supported x64 and x86 installers. On macOS, the project points to Homebrew installation. Linux users can use Snap, while packages or repositories are listed for Debian, Raspberry Pi and Ubuntu. This breadth makes it practical for mixed device estates and for moving from a small board to a server without changing broker software.

Who it's for

Choose Mosquitto for IoT and machine-to-machine systems that need standard MQTT versions, configurable delivery behavior and a broker that can fit constrained hardware. It is particularly appropriate when on-premises control matters or when developers need supplied C and command-line clients. It is a weaker choice for organizations seeking a fully managed broker, bundled service-level support or an administration experience that removes infrastructure work; those needs require Cedalo services or another product.

Pros and cons

Pros

• Free core software: the open-source plan costs 0.00 USD and includes core MQTT features on premises.
• Broad MQTT coverage: MQTT 5.0, 3.1.1 and 3.1 support covers current and established clients.
• Lightweight deployment: it can suit low-power single-board computers as well as servers.
• Useful companion tools: a C client library and command-line publisher/subscriber tools support development and operations.
• Flexible connection security: the public test server supports plain MQTT, TLS, client-certificate TLS and WebSockets.

Cons

• Self-managed operations: on-premises delivery leaves infrastructure, maintenance and availability work with your team.
• Best-effort community help: GitHub, mailing-list, Matrix and forum support does not promise commercial response times.
• No bundled managed tier: hosted operation and consulting come through separate Cedalo services with custom pricing.

Alternatives

EMQX is the better fit when you want a freemium serverless option with up to 1,000 connections and usage-based billing beyond its monthly free quota.

Aiven for Apache Kafka suits teams that prefer a managed Kafka service; its free plan specifies 250 KiB/s throughput, three days of retention, five topics and two partitions per topic.

Apache Pulsar, Apache Qpid Broker-J and Apache RocketMQ are free, open-source broker alternatives when their respective messaging ecosystems are a better match.

Confluent Cloud is preferable for a managed Kafka deployment with autoscaling resources and managed connectors on its free Basic tier.

HiveMQ MQTT Broker is worth considering when a defined connection and message-rate allowance or paid commercial tiers matter; its Lab plan states 100 connections and 100 messages per second.

RabbitMQ is another free, self-managed broker with community-based support under the Mozilla Public License 2.0.

For broader comparisons, see Message Queue (MQ) Software and Message Broker Software.

Verdict

Mosquitto is a strong recommendation for IoT developers and operators who want a no-cost, standards-based MQTT broker that can run from a small board to a server and remain under their control. Choose it for its lightweight footprint and practical client tooling; look elsewhere when managed hosting, guaranteed commercial support or a fully operated service is the priority.